The Raman spectra of Co<sub>3</sub>O<sub>4</sub>

Hadjiev, V. G.; Iliev, M. N.; Vergilov, I.

doi:10.1088/0022-3719/21/7/007

Cited by 894 publications

(430 citation statements)

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“…In fact, this spectroscopic technique is highly sensitive to oxygen displacement, owing to its high polarizability and to intermediate range order For Co 3 O 4 spinel structure (Co 2+ located at the tetrahedral site (Td) and Co 3+ at the octahedral one (Oh)), Raman peaks are predicted to appear at 194 cm -1 (F2g), 485 cm -1 (Eg), 523 cm -1 (F2g), 620 cm -1 (F2g, Td site), and at 693 cm -1 (A1g; Oh site) [45].…”

Section: Introductionmentioning

confidence: 99%

Total Oxidation of Naphthalene with Zirconia-Supported Cobalt, Copper and Nickel Catalysts

et al. 2017

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ZrO 2 ·nH 2 O (hydrogel) impregnated with transition metals (Cu, Co, and Ni) was studied in this work as a precursor for the synthesis of CuO/ZrO 2 (CuZ), CoO x /ZrO 2 (CoZ), and NiO/ZrO 2 (NiZ) catalysts, employed in the naphthalene oxidation reaction. Fresh and catalytically used materials were characterized by different physicochemical techniques, to compare the bulk and surface behavior, with particular attention to the effect of the supported metal species' properties on the catalytic activity. Techniques such as X-ray diffraction (XRD), temperature programmed reduction (TPR), differential scanning calorimetry (DSC), Brunauer-Emmett-Teller (BET) surface area analyzer, diffuse reflectance spectroscopy (DRS UV-vis), and Raman spectroscopy, allow for establishing structural and textural aspects of the support, as well as the surface coordination and the accessibility of supported species. Results were in agreement with the CuZ > CoZ > NiZ sequence for the activity in naphthalene oxidation reaction. Electronic properties, ionic sizes, oxide phase deposition on the support surface, reducibility, metal-support interaction, and local site symmetry of metals seem to be decisive factors for the catalytic interaction with the gaseous phase.

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Section: Introductionmentioning

confidence: 99%

Total Oxidation of Naphthalene with Zirconia-Supported Cobalt, Copper and Nickel Catalysts

et al. 2017

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“…1b). The Raman spectra of cobalt spinel sample is characterized by five resolved Raman bands at about 194 (F 2g ), 480 (E g ), 520 (F 2g ), 620 (F 2g ), and 690 (A 1g ) cm -1 , predicted by the factor analysis [33], which also confirms absence of any minor spurious phases.…”

Section: Catalyst Characterizationmentioning

confidence: 52%

Surface oxygen dynamics and H2 oxidation on cobalt spinel surface probed by 18O/16O isotopic exchange and accounted for by DFT molecular modeling: facile interfacial oxygen atoms flipping through transient peroxy intermediate

et al. 2016

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Surface dynamics of reactive oxygen species (ROS) and hydrogen oxidation on cobalt spinel nanocatalyst, faceted predominantly with (100) 2-peroxy unit requires 0.39 eV only, opening an easy pathway for rapid isotopic exchange without explicit formation of energetically more costly oxygen vacancies. The latter may occur effectively at T [ 700°C. The catalytic activity of ROS species was probed by H 2 oxidation reaction. The diatomic ROS reactivity (below 160°C) is characterized by E a = 16 kcal/mol, and for monoatomic species (between 160°C and 300°C) it falls to E a = 9.2 kcal/mol. It was shown that suprafacial dehydroxylation of ROS generated water is energetically less costly (E a = 1.15 eV) than intrafacial dehydroxylation (E a = 1.71 eV) entailing removal of water associated with the lattice oxygen. Thus, the former may operate even at relatively low temperatures (below 300-350°C). The appearance of significant amount of H 2 16 O in the reaction products is related to easy isotopic 18 O/ 16 O scrambling via transient peroxo intermediates, and is not diagnostic of direct involvement of the Mars van Krevelen mechanism.

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“…Figure 5 showed the Raman spectra of the Co/Al2O3 and Co/SO4 2-/Al2O3 catalysts before and after the reaction. The spectrum shows clearly the Raman peaks at 203, 485, 530, 624 and 692 cm -1 in the range of 100-1000 cm -1 , which correspond respectively to the F 1 2 g, Eg, F 2 2 g, F 3 2 g and A1 g modes of crystalline Co3O4 or CoAl2O4 18) . There were almost no differences in all catalysts.…”

Section: Catalyst Structurementioning

confidence: 95%

Active Species of Sulfated Metal Oxide Catalyst for Propane Dehydrogenation

Watanabe

Hirata

Fukuhara

2017

J. Jpn. Petrol. Inst.

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This study focuses on clarifying the active species over a sulfated transition metal oxide (Cr, Mn, Fe, Co, Ni, Cu) catalyst for propane dehydrogenation. The unsulfated catalyst showed a high conversion for the dehydrogenation of propane, with significantly low selectivity to the desired product of propylene. On the other hand, the sulfated catalyst displayed a high selectivity to propylene, though the conversion was slightly decreased. The sulfation treatment was especially effective for the Co and Fe catalysts. The sulfate species (SO4 2-) were reduced to the active species of the sulfide ion (S 2-) in the reaction atmosphere, which increased a selectivity to propylene.

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The Raman spectra of Co₃O₄

Cited by 894 publications

References 4 publications

Total Oxidation of Naphthalene with Zirconia-Supported Cobalt, Copper and Nickel Catalysts

Total Oxidation of Naphthalene with Zirconia-Supported Cobalt, Copper and Nickel Catalysts

Surface oxygen dynamics and H2 oxidation on cobalt spinel surface probed by 18O/16O isotopic exchange and accounted for by DFT molecular modeling: facile interfacial oxygen atoms flipping through transient peroxy intermediate

Active Species of Sulfated Metal Oxide Catalyst for Propane Dehydrogenation

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The Raman spectra of Co3O4

Cited by 894 publications

References 4 publications

Total Oxidation of Naphthalene with Zirconia-Supported Cobalt, Copper and Nickel Catalysts

Total Oxidation of Naphthalene with Zirconia-Supported Cobalt, Copper and Nickel Catalysts

Surface oxygen dynamics and H2 oxidation on cobalt spinel surface probed by 18O/16O isotopic exchange and accounted for by DFT molecular modeling: facile interfacial oxygen atoms flipping through transient peroxy intermediate

Active Species of Sulfated Metal Oxide Catalyst for Propane Dehydrogenation

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The Raman spectra of Co₃O₄